Multicomponent Biodegradable Filaments and Nonwoven Webs Formed Therefrom

ABSTRACT

A biodegradable, substantially continuous filament is provided. The filament contains a first component formed from at least one high melting polyester and a second component formed from at least one low melting polyester. The low melting point polyester is an aliphatic-aromatic copolyester formed by melt blending a polymer and an alcohol to initiate an alcoholysis reaction that results in a copolyester having one or more hydroxyalkyl or alkyl terminal groups. By selectively controlling the alcoholysis conditions (e.g., alcohol and copolymer concentrations, catalysts, temperature, etc.), a modified aliphatic-aromatic copolyester may be achieved that has a molecular weight lower than the starting aliphatic-aromatic polymer. Such lower molecular weight polymers also have the combination of a higher melt flow index and lower apparent viscosity, which is useful in the formation of substantially continuous filaments.

BACKGROUND OF THE INVENTION

Biodegradable nonwoven webs are useful in a wide range of applications,such as in the formation of disposable absorbent products (e.g.,diapers, training pants, sanitary wipes, feminine pads and liners, adultincontinence pads, guards, garments, etc.) and/or health care products(e.g., surgical gowns, drapes, etc.). To facilitate formation of thenonwoven web, a biodegradable polymer should be selected that is meltprocessable, yet also has good mechanical and physical properties.Biodegradable aliphatic-aromatic copolyesters have been developed thatpossess good mechanical and physical properties. Unfortunately, the highmolecular weight and viscosity of aliphatic-aromatic copolyesters hasgenerally prevented their use in certain fiber forming processes. Forexample, conventional aliphatic-aromatic copolyesters are not typicallysuitable for meltblowing processes, which require a low polymerviscosity for successful microfiber formation. As such, a need currentlyexists for a biodegradable aliphatic-aromatic copolyester that exhibitsgood mechanical and physical properties, but which may be readily formedinto a nonwoven web using a variety of techniques (e.g., meltblowing).

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, abiodegradable, substantially continuous multicomponent filament isdisclosed that comprises a first component and a second component. Thefirst component contains a first polyester having a melting point offrom about 150° C. to about 250° C. and the second component contains asecond polyester. The second polyester is an aliphatic-aromaticcopolyester terminated with an alkyl group, hydroxyalkyl group, or acombination thereof. The aliphatic-aromatic copolyester has a melt flowindex of from about 5 to about 200 grams per 10 minutes, determined at aload of 2160 grams and temperature of 190° C. in accordance with ASTMTest Method D1238-E.

In accordance with another embodiment of the present invention, a methodfor forming biodegradable, substantially continuous multicomponentfilaments is disclosed. The method comprises forming a firstthermoplastic composition that contains a first polyester having amelting point of from about 150° C. to about 250° C. and forming asecond thermoplastic composition by melt blending a precursoraliphatic-aromatic copolyester with at least one alcohol so that thecopolyester undergoes an alcoholysis reaction. The alcoholysis reactionresults in a modified copolyester having a melt flow index that isgreater than the melt flow index of the precursor copolyester,determined at a load of 2160 grams and temperature of 190° C. inaccordance with ASTM Test Method D1238-E. The first thermoplasticcomposition and the second thermoplastic composition are co-extruded toform substantially continuous filaments.

Other features and aspects of the present invention are discussed ingreater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth more particularly in the remainder of the specification, whichmakes reference to the appended figures in which:

FIG. 1 is a schematic illustration of a process that may be used in oneembodiment of the present invention to form a continuous filament web;

FIG. 2 is a graph depicting apparent viscosity versus various shearrates for the extruded resins of Example 1;

FIG. 3 is a graph depicting apparent viscosity versus various shearrates for the extruded resins of Example 3; and

FIG. 4 is a graph depicting apparent viscosity versus various shearrates for the extruded resins of Example 4.

Repeat use of references characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

Reference now will be made in detail to various embodiments of theinvention, one or more examples of which are set forth below. Eachexample is provided by way of explanation of the invention, notlimitation of the invention. In fact, it will be apparent to thoseskilled in the art that various modifications and variations may be madein the present invention without departing from the scope or spirit ofthe invention. For instance, features illustrated or described as partof one embodiment, may be used on another embodiment to yield a stillfurther embodiment. Thus, it is intended that the present inventioncovers such modifications and variations as come within the scope of theappended claims and their equivalents.

DEFINITIONS

As used herein, the term “biodegradable” or “biodegradable polymer”generally refers to a material that degrades from the action ofnaturally occurring microorganisms, such as bacteria, fungi, and algae;environmental heat; moisture; or other environmental factors. Thebiodegradability of a material may be determined using ASTM Test Method5338.92.

As used herein, the term “continuous filament web” generally refers to anonwoven web containing substantially continuous filaments. Thefilaments may, for example, have a length much greater than theirdiameter, such as a length to diameter ratio (“aspect ratio”) greaterthan about 15,000 to 1, and in some cases, greater than about 50,000 to1.

As used herein, the term “nonwoven web” refers to a web having astructure of individual threads (e.g., fibers or filaments) that arerandomly interlaid, not in an identifiable manner as in a knittedfabric. Nonwoven webs include, for example, meltblown webs, spunbondwebs, carded webs, wet-laid webs, airlaid webs, coform webs,hydraulically entangled webs, etc. The basis weight of the nonwoven webmay generally vary, but is typically from about 5 grams per square meter(“gsm”) to 200 gsm, in some embodiments from about 10 gsm to about 150gsm, and in some embodiments, from about 15 gsm to about 100 gsm.

As used herein, the term “meltblown web” generally refers to a nonwovenweb that is formed by a process in which a molten thermoplastic materialis extruded through a plurality of fine, usually circular, diecapillaries as molten fibers into converging high velocity gas (e.g.air) streams that attenuate the fibers of molten thermoplastic materialto reduce their diameter, which may be to microfiber diameter.Thereafter, the meltblown fibers are carried by the high velocity gasstream and are deposited on a collecting surface to form a web ofrandomly dispersed meltblown fibers. Such a process is disclosed, forexample, in U.S. Pat. No. 3,849,241 to Butin, et al., which isincorporated herein in its entirety by reference thereto for allpurposes. Generally speaking, meltblown fibers may be microfibers thatare substantially continuous or discontinuous, generally smaller than 10micrometers in diameter, and generally tacky when deposited onto acollecting surface.

As used herein, the term “spunbond web” generally refers to a webcontaining small diameter substantially continuous filaments. Thefilaments are formed by extruding a molten thermoplastic material from aplurality of fine, usually circular, capillaries of a spinnerette withthe diameter of the extruded filaments then being rapidly reduced as by,for example, eductive drawing and/or other well-known spunbondingmechanisms. The production of spunbond webs is described andillustrated, for example, in U.S. Pat. Nos. 4,340,563 to Appel, et al.,3,692,618 to Dorschner, et al., 3,802,817 to Matsuki, et al., 3,338,992to Kinney, 3,341,394 to Kinney, 3,502,763 to Hartman, 3,502,538 to Levy,3,542,615 to Dobo, et al., and 5,382,400 to Pike, et al., which areincorporated herein in their entirety by reference thereto for allpurposes. Spunbond filaments are generally not tacky when they aredeposited onto a collecting surface. Spunbond filaments may sometimeshave diameters less than about 40 micrometers, and are often betweenabout 5 to about 20 micrometers.

As used herein, the term “multicomponent” refers to filaments formedfrom at least two polymer components (e.g., bicomponent filaments).

DETAILED DESCRIPTION

The present invention is directed to a substantially continuous filamentthat is biodegradable. The filament contains a first component formedfrom at least one high melting polyester and a second component formedfrom at least one low melting polyester. The first and second componentsmay be arranged in any desired configuration, such as sheath-core,side-by-side, pie, island-in-the-sea, and so forth. Regardless, the lowmelting point polyester is an aliphatic-aromatic copolyester formed bymelt blending a polymer and an alcohol to initiate an alcoholysisreaction that results in a copolyester having one or more hydroxyalkylor alkyl terminal groups. By selectively controlling the alcoholysisconditions (e.g., alcohol and copolymer concentrations, catalysts,temperature, etc.), a modified aliphatic-aromatic copolyester may beachieved that has a molecular weight lower than the startingaliphatic-aromatic polymer. Such lower molecular weight polymers alsohave the combination of a higher melt flow index and lower apparentviscosity, which is useful in the formation of substantially continuousfilaments.

I. First Component

As stated, the first component of the multicomponent filaments is formedfrom one or more “high melting point” biodegradable polyesters. Themelting point of such polyesters is from about 150° C. to about 250° C.,in some embodiments from about 160° C. to about 240° C., and in someembodiments, from about 170° C. to about 220° C. Various “high meltingpoint” polyesters may be employed in the present invention, such aspolyesteramides, modified polyethylene terephthalate, polylactic acid(PLA), terpolymers based on polylactic acid, polyglycolic acid,polyalkylene carbonates (such as polyethylene carbonate),polyhydroxyalkanoates (PHA), polyhydroxybutyrates (PHB),polyhydroxyvalerates (PHV), and polyhydroxybutyrate-hydroxyvaleratecopolymers (PHBV). The term “polylactic acid” generally refers tohomopolymers of lactic acid, such as poly(L-lactic acid), poly(D-lacticacid), poly(DL-lactic acid), mixtures thereof, and copolymers containinglactic acid as the predominant component and a small proportion of acopolymerizable comonomer, such as 3-hydroxybutyrate, caprolactone,glycolic acid, etc. One particularly suitable polylactic acid polymerthat may be used in the present invention is commercially available fromBiomer, Inc. (Germany) under the name Biomer™ L9000. Still othersuitable polylactic acid polymers are commercially available fromNatureworks, LLC of Minneapolis, Minn.

Although not required, the high melting point polyesters typicallyconstitute the principal ingredient of the first component. That is, thepolyesters may constitute at least about 80 wt. %, in some embodimentsat least about 90 wt. %, and in some embodiments, at least about 95 wt.% of the first component. In such embodiments, the characteristics ofthe first component (e.g., melting point) will be substantially the sameas the characteristics of the polyesters employed. For example, themelting point of the first component may range from about 150° C. toabout 250° C., in some embodiments from about 160° C. to about 240° C.,and in some embodiments, from about 170° C. to about 220° C.

II. Second Component

The second component is formed from one or more “low melting point”biodegradable aromatic-aliphatic copolyesters. Such copolyesters have amelting point of from about 50° C. to about 150° C., in some embodimentsfrom about 80° C. to about 140° C., and in some embodiments, from about90° C. to about 130° C. Moreover, the melting point is also typically atleast about 30° C., in some embodiments at least about 40° C., and insome embodiments, at least about 50° C. less than the melting point ofthe “high melting point” polyesters. In addition, they are generallysofter to the touch than most “high melting point” polyesters. The glasstransition temperature (“T_(g)”) of the low melting point copolyestersmay also be less than that of the high melting point polyesters toimprove flexibility and processability of the polymers. For example, thelow melting point copolyesters may have a T_(g) of about 25° C. or less,in some embodiments about 0° C. or less, and in some embodiments, about−10° C. or less. Such a glass transition temperature may be at leastabout 5° C., in some embodiments at least about 10° C., and in someembodiments, at least about 15° C. less than the glass transitiontemperature of the high melting point polyesters. As discussed in moredetail below, the melting temperature and glass transition temperaturemay be determined using differential scanning calorimetry (“DSC”) inaccordance with ASTM D-3417.

Generally speaking, the aliphatic-aromatic copolyesters are formed bymelt blending a polymer an alcohol to initiate an alcoholysis reactionthat results in a copolyester having one or more hydroxyalkyl or alkylterminal groups. Various embodiments of the alcoholysis reactioncomponents and techniques will now be described in more detail below.

III. Reaction Components

A. Aliphatic-Aromatic Copolyester

The aliphatic-aromatic copolyester may be synthesized using any knowntechnique, such as through the condensation polymerization of a polyolin conjunction with aliphatic and aromatic dicarboxylic acids oranhydrides thereof. The polyols may be substituted or unsubstituted,linear or branched, polyols selected from polyols containing 2 to about12 carbon atoms and polyalkylene ether glycols containing 2 to 8 carbonatoms. Examples of polyols that may be used include, but are not limitedto, ethylene glycol, diethylene glycol, propylene glycol,1,2-propanediol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol,1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol,1,5-pentanediol, 1,6-hexanediol, polyethylene glycol, diethylene glycol,2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, cyclopentanediol, triethyleneglycol, and tetraethylene glycol. Preferred polyols include1,4-butanediol; 1,3-propanediol; ethylene glycol; 1,6-hexanediol;diethylene glycol; and 1,4-cyclohexanedimethanol.

Representative aliphatic dicarboxylic acids that may be used includesubstituted or unsubstituted, linear or branched, non-aromaticdicarboxylic acids selected from aliphatic dicarboxylic acids containing2 to about 12 carbon atoms, and derivatives thereof. Non-limitingexamples of aliphatic dicarboxylic acids include malonic, succinic,oxalic, glutaric, adipic, pimelic, azelaic, sebacic, fumaric,2,2-dimethyl glutaric, suberic, 1,3-cyclopentanedicarboxylic,1,4-cyclohexanedicarboxylic, 1,3-cyclohexanedicarboxylic, diglycolic,itaconic, maleic, and 2,5-norbornanedicarboxylic. Representativearomatic dicarboxylic acids that may be used include substituted andunsubstituted, linear or branched, aromatic dicarboxylic acids selectedfrom aromatic dicarboxylic acids containing 1 to about 6 carbon atoms,and derivatives thereof. Non-limiting examples of aromatic dicarboxylicacids include terephthalic acid, dimethyl terephthalate, isophthalicacid, dimethyl isophthalate, 2,6-napthalene dicarboxylic acid,dimethyl-2,6-naphthalate, 2,7-naphthalenedicarboxylic acid,dimethyl-2,7-naphthalate, 3,4′-diphenyl ether dicarboxylic acid,dimethyl-3,4′diphenyl ether dicarboxylate, 4,4′-diphenyl etherdicarboxylic acid, dimethyl-4,4′-diphenyl ether dicarboxylate,3,4′-diphenyl sulfide dicarboxylic acid, dimethyl-3,4′-diphenyl sulfidedicarboxylate, 4,4′-diphenyl sulfide dicarboxylic acid,dimethyl-4,4′-diphenyl sulfide dicarboxylate, 3,4′-diphenyl sulfonedicarboxylic acid, dimethyl-3,4′-diphenyl sulfone dicarboxylate,4,4′-diphenyl sulfone dicarboxylic acid, dimethyl-4,4′-diphenyl sulfonedicarboxylate, 3,4′-benzophenonedicarboxylic acid,dimethyl-3,4′-benzophenonedicarboxylate, 4,4′-benzophenonedicarboxylicacid, dimethyl-4,4′-benzophenonedicarboxylate, 1,4-naphthalenedicarboxylic acid, dimethyl-1,4-naphthalate, 4,4′-methylene bis(benzoicacid), dimethyl-4,4′-methylenebis(benzoate), etc., and mixtures thereof.

The polymerization may be catalyzed by a catalyst, such as atitanium-based catalyst (e.g., tetraisopropyltitanate, tetraisopropoxytitanium, dibutoxydiacetoacetoxy titanium, or tetrabutyltitanate). Ifdesired, a diisocyanate chain extender may be reacted with thecopolyester to increase its molecular weight. Representativediisocyanates may include toluene 2,4-diisocyanate, toluene2,6-diisocyanate, 2,4′-diphenylmethane diisocyanate,naphthylene-1,5-diisocyanate, xylylene diisocyanate, hexamethylenediisocyanate (“HMDI”), isophorone diisocyanate andmethylenebis(2-isocyanatocyclohexane). Trifunctional isocyanatecompounds may also be employed that contain isocyanurate and/or biureagroups with a functionality of not less than three, or to replace thediisocyanate compounds partially by tri- or polyisocyanates. Thepreferred diisocyanate is hexamethylene diisocyanate. The amount of thechain extender employed is typically from about 0.3 to about 3.5 wt. %,in some embodiments, from about 0.5 to about 2.5 wt. % based on thetotal weight percent of the polymer.

The copolyesters may either be a linear polymer or a long-chain branchedpolymer. Long-chain branched polymers are generally prepared by using alow molecular weight branching agent, such as a polyol, polycarboxylicacid, hydroxy acid, and so forth. Representative low molecular weightpolyols that may be employed as branching agents include glycerol,trimethylolpropane, trimethylolethane, polyethertriols, glycerol,1,2,4-butanetriol, pentaerythritol, 1,2,6-hexanetriol, sorbitol,1,1,4,4,-tetrakis(hydroxymethyl)cyclohexane,tris(2-hydroxyethyl)isocyanurate, and dipentaerythritol. Representativehigher molecular weight polyols (molecular weight of 400 to 3000) thatmay be used as branching agents include triols derived by condensingalkylene oxides having 2 to 3 carbons, such as ethylene oxide andpropylene oxide with polyol initiators. Representative polycarboxylicacids that may be used as branching agents include hemimellitic acid,trimellitic (1,2,4-benzenetricarboxylic) acid and anhydride, trimesic(1,3,5-benzenetricarboxylic) acid, pyromellitic acid and anhydride,benzenetetracarboxylic acid, benzophenone tetracarboxylic acid,1,1,2,2-ethane-tetracarboxylic acid, 1,1,2-ethanetricarboxylic acid,1,3,5-pentanetricarboxylic acid, and 1,2,3,4-cyclopentanetetracarboxylicacid. Representative hydroxy acids that may be used as branching agentsinclude malic acid, citric acid, tartaric acid, 3-hydroxyglutaric acid,mucic acid, trihydroxyglutaric acid, 4-carboxyphthalic anhydride,hydroxyisophthalic acid, and 4-(beta-hydroxyethyl)phthalic acid. Suchhydroxy acids contain a combination of 3 or more hydroxyl and carboxylgroups. Especially preferred branching agents include trimellitic acid,trimesic acid, pentaerythritol, trimethylol propane and1,2,4-butanetriol.

The aromatic dicarboxylic acid monomer constituent may be present in thecopolyester in an amount of from about 10 mole % to about 40 mole %, insome embodiments from about 15 mole % to about 35 mole %, and in someembodiments, from about 15 mole % to about 30 mole %. The aliphaticdicarboxylic acid monomer constituent may likewise be present in thecopolyester in an amount of from about 15 mole % to about 45 mole %, insome embodiments from about 20 mole % to about 40 mole %, and in someembodiments, from about 25 mole % to about 35 mole %. The polyol monomerconstituent may also be present in the aliphatic-aromatic copolyester inan amount of from about 30 mole % to about 65 mole %, in someembodiments from about 40 mole % to about 50 mole %, and in someembodiments, from about 45 mole % to about 55 mole %.

In one particular embodiment, for example, the aliphatic-aromaticcopolyester may comprise the following structure:

wherein,

m is an integer from 2 to 10, in some embodiments from 2 to 4, and inone embodiment, 4;

n is an integer from 0 to 18, in some embodiments from 2 to 4, and inone embodiment, 4;

p is an integer from 2 to 10, in some embodiments from 2 to 4, and inone embodiment, 4;

x is an integer greater than 1; and

y is an integer greater than 1. One example of such a copolyester ispolybutylene adipate terephthalate, which is commercially availableunder the designation ECOFLEX® F BX 7011 from BASF Corp. Another exampleof a suitable copolyester containing an aromatic terephtalic acidmonomer constituent is available under the designation ENPOL™ 8060M fromIRE Chemicals (South Korea). Other suitable aliphatic-aromaticcopolyesters may be described in U.S. Pat. Nos. 5,292,783; 5,446,079;5,559,171; 5,580,911; 5,599,858; 5,817,721; 5,900,322; and 6,258,924,which are incorporated herein in their entirety by reference thereto forall purposes.

The aliphatic-aromatic polyester typically has a number averagemolecular weight (“M_(n)”) ranging from about 40,000 to about 120,000grams per mole, in some embodiments from about 50,000 to about 100,000grams per mole, and in some embodiments, from about 60,000 to about85,000 grams per mole. Likewise, the polymer also typically has a weightaverage molecular weight (“M_(w)”) ranging from about 70,000 to about240,000 grams per mole, in some embodiments from about 80,000 to about190,000 grams per mole, and in some embodiments, from about 100,000 toabout 150,000 grams per mole. The ratio of the weight average molecularweight to the number average molecular weight (“M_(w)/M_(n)”), i.e., the“polydispersity index”, is also relatively low. For example, thepolydispersity index typically ranges from about 1.0 to about 3.0, insome embodiments from about 1.2 to about 2.0, and in some embodiments,from about 1.4 to about 1.8. The weight and number average molecularweights may be determined by methods known to those skilled in the art.

The aromatic-aliphatic polyester may also have an apparent viscosity offrom about 100 to about 1000 Pascal seconds (Pa·s), in some embodimentsfrom about 200 to about 800 Pas, and in some embodiments, from about 300to about 600 Pa·s, as determined at a temperature of 170° C. and a shearrate of 1000 sec⁻¹. The melt flow index of the aromatic-aliphaticpolyester may also range from about 0.1 to about 10 grams per 10minutes, in some embodiments from about 0.5 to about 8 grams per 10minutes, and in some embodiments, from about 1 to about 5 grams per 10minutes. The melt flow index is the weight of a polymer (in grams) thatmay be forced through an extrusion rheometer orifice (0.0825-inchdiameter) when subjected to a load of 2160 grams in 10 minutes at acertain temperature (e.g., 190° C.), measured in accordance with ASTMTest Method D1238-E.

B. Alcohol

As indicated above, the aliphatic-aromatic copolyester may be reactedwith an alcohol to form a modified copolyester having a reducedmolecular weight. The concentration of the alcohol reactant mayinfluence the extent to which the molecular weight is altered. Forinstance, higher alcohol concentrations generally result in a moresignificant decrease in molecular weight. Of course, too high of analcohol concentration may also affect the physical characteristics ofthe resulting polymer. Thus, in most embodiments, the alcohol(s) areemployed in an amount of about 0.1 wt. % to about 10 wt. %, in someembodiments from about 0.1 wt. % to about 4 wt. %, and in someembodiments, from about 0.2 wt. % to about 1 wt. %, based on the totalweight of the starting aliphatic-aromatic copolyester.

The alcohol may be monohydric or polyhydric (dihydric, trihydric,tetrahydric, etc.), saturated or unsaturated, and optionally substitutedwith functional groups, such as carboxyl, amine, etc. Examples ofsuitable monohydric alcohols include methanol, ethanol, 1-propanol,2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol,1-hexanol, 2-hexanol, 3-hexanol, 1-heptanol, 2-heptanol, 3-heptanol,4-heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 1-nonanol,2-nonanol, 3-nonanol, 4-nonanol, 5-nonanol, 1-decanol, 2-decanol,3-decanol, 4-decanol, 5-decanol, allyl alcohol, 1-butenol, 2-butenol,1-pentenol, 2-pentenol, 1-hexenol, 2-hexenol, 3-hexenol, 1-heptenol,2-heptenol, 3-heptenol, 1-octenol, 2-octenol, 3-octenol, 4-octenol,1-nonenol, 2-nonenol, 3-nonenol, 4-nonenol, 1-decenol, 2-decenol,3-decenol, 4-decenol, 5-decenol, cyclohexanol, cyclopentanol,cycloheptanol, 1-phenylhyl alcohol, 2-phenylhyl alcohol,2-ethoxy-ethanol, methanolamine, ethanolamine, and so forth. Examples ofsuitable dihydric alcohols include 1,3-propanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol,1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol,1-hydroxymethyl-2-hydroxyethylcyclohexane,1-hydroxy-2-hydroxypropylcyclohexane,1-hydroxy-2-hydroxyethylcyclohexane,1-hydroxymethyl-2-hydroxyethylbenzene,1-hydroxymethyl-2-hydroxypropylbenzene, 1-hydroxy-2-hydroxyethylbenzene,1,2-benzylmethylol, 1,3-benzyldimethylol, and so forth. Suitabletrihydric alcohols may include glycerol, trimethylolpropane, etc., whilesuitable tetrahydric alcohols may include pentaerythritol, erythritol,etc. Preferred alcohols are dihydric alcohols having from 2 to 6 carbonatoms, such as 1,3-propanediol and 1,4-butanediol.

The hydroxy group of the alcohol is generally capable of attacking anester linkage of the aliphatic-aromatic copolyester, thereby leading tochain scission or “depolymerization” of the copolyester molecule intoone or more shorter ester chains. The shorter chains may includealiphatic-aromatic polyesters or oligomers, as well as minor portions ofaliphatic polyesters or oligomers, aromatic polyesters or oligomers, andcombinations of any of the foregoing. Although not necessarily required,the short chain aliphatic-aromatic polyesters formed during alcoholysisare often terminated with an alkyl and/or hydroxyalkyl groups derivedfrom the alcohol. Alkyl group terminations are typically derived frommonohydric alcohols, while hydroxyalkyl group terminations are typicallyderived from polyhydric alcohols. In one particular embodiment, forexample, an aliphatic-aromatic copolyester is formed during thealcoholysis reaction that comprises the following general structure:

wherein,

m is an integer from 2 to 10, in some embodiments from 2 to 4, and inone embodiment, 4;

n is an integer from 0 to 18, in some embodiments from 2 to 4, and inone embodiment, 4;

p is an integer from 2 to 10, in some embodiments from 2 to 4, and inone embodiment, 4;

x is an integer greater than 1;

y is an integer greater than 1; and

R₁ and R₂ are independently selected from hydrogen; hydroxyl groups;straight chain or branched, substituted or unsubstituted C₁-C₁₀ alkylgroups; straight chain or branched, substituted or unsubstituted C₁-C₁₀hydroxalkyl groups. Preferably, at least one of R₁ and R₂, or both, arestraight chain or branched, substituted or unsubstituted, C₁-C₁₀ alkylor C₁-C₁₀ hydroxyalkyl groups, in some embodiments C₁-C₈ alkyl or C₁-C₈hydroxyalkyl groups, and in some embodiments, C₂-C₆ alkyl or C₂-C₆hydroxyalkyl groups. Examples of suitable alkyl and hydroxyalkyl groupsinclude, for instance, methyl, ethyl, iso-propyl, n-propyl, n-butyl,isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl,n-decyl, 1-hydroxyethyl, 2-hydroxyethyl, 3-hydroxypropyl,4-hydroxybutyl, and 5-hydroxypentyl groups. Thus, as indicated, themodified aliphatic-aromatic copolyester has a different chemicalcomposition than an unmodified copolyester in terms of its terminalgroups. The terminal groups may play a substantial role in determiningthe properties of the polymer, such as its reactivity, stability, etc.

Regardless of its particular structure, a new polymer species is formedduring alcoholysis that has a molecular weight lower than that of thestarting polyester. The weight average and/or number average molecularweights may, for instance, each be reduced so that the ratio of thestarting copolyester molecular weight to the new molecular weight is atleast about 1.1, in some embodiments at least about 1.4, and in someembodiments, at least about 1.6. For example, the modifiedaliphatic-aromatic copolyester may have a number average molecularweight (“M_(n)”) ranging from about 10,000 to about 70,000 grams permole, in some embodiments from about 20,000 to about 60,000 grams permole, and in some embodiments, from about 30,000 to about 55,000 gramsper mole. Likewise, the modified copolyester may also have a weightaverage molecular weight (“M_(w)”) of from about 20,000 to about 125,000grams per mole, in some embodiments from about 30,000 to about 110,000grams per mole, and in some embodiments, from about 40,000 to about90,000 grams per mole.

In addition to possessing a lower molecular weight, the modifiedaliphatic-aromatic copolyester may also have a lower apparent viscosityand higher melt flow index than the starting polyester. The apparentviscosity may for instance, be reduced so that the ratio of the startingcopolyester viscosity to the modified copolyester viscosity is at leastabout 1.1, in some embodiments at least about 2, and in someembodiments, from about 10 to about 40. Likewise, the melt flow indexmay be increased so that the ratio of the modified copolyester melt flowindex to the starting copolyester melt flow index is at least about 1.5,in some embodiments at least about 3, in some embodiments at least about10, and in some embodiments, from about 20 to about 200. In oneparticular embodiment, the modified copolyester may have an apparentviscosity of from about 10 to about 500 Pascal seconds (Pa·s), in someembodiments from about 20 to about 400 Pa·s, and in some embodiments,from about 30 to about 250 Pa·s, as determined at a temperature of 170°C. and a shear rate of 1000 sec⁻¹. The melt flow index (190° C., 2.16kg) of the modified copolyester may range from about 5 to about 200grams per 10 minutes, in some embodiments from about 10 to about 100grams per 10 minutes, and in some embodiments, from about 15 to about 50grams per 10 minutes. Of course, the extent to which the molecularweight, apparent viscosity, and/or melt flow index are altered by thealcoholysis reaction may vary depending on the intended application.

Although differing from the starting polymer in certain properties, themodified copolyester may nevertheless retain other properties of thestarting polymer to enhance the flexibility and processability of thepolymers. For example, the thermal characteristics (e.g., T_(g), T_(m),and latent heat of fusion) typically remain substantially the same asthe starting polymer, such as within the ranges noted above. Further,even though the actual molecular weights may differ, the polydispersityindex of the modified copolyester may remain substantially the same asthe starting polymer, such as within the range of about 1.0 to about3.0, in some embodiments from about 1.1 to about 2.0, and in someembodiments, from about 1.2 to about 1.8.

Typically, modified aliphatic-aromatic copolyesters constitute theprincipal ingredient of the second component. That is, the modifiedcopolyesters may constitute at least about 90 wt. %, in some embodimentsat least about 92 wt. %, and in some embodiments, at least about 95 wt.% of the second component. In such embodiments, the characteristics ofthe second component (e.g., melting point) will be substantially thesame as the characteristics of the modified copolyesters employed.

C. Catalyst

A catalyst may be employed to facilitate the modification of thealcoholysis reaction. The concentration of the catalyst may influencethe extent to which the molecular weight is altered. For instance,higher catalyst concentrations generally result in a more significantdecrease in molecular weight. Of course, too high of a catalystconcentration may also affect the physical characteristics of theresulting polymer. Thus, in most embodiments, the catalyst(s) areemployed in an amount of about 50 to about 2000 parts per million(“ppm”), in some embodiments from about 100 to about 1000 ppm, and insome embodiments, from about 200 to about 1000 ppm, based on the weightof the starting aliphatic-aromatic copolyester.

Any known catalyst may be used in the present invention to accomplishthe desired reaction. In one embodiment, for example, a transition metalcatalyst may be employed, such as those based on Group IVB metals and/orGroup IVA metals (e.g., alkoxides or salts). Titanium-, zirconium-,and/or tin-based metal catalysts are especially desirable and mayinclude, for instance, titanium butoxide, titanium tetrabutoxide,titanium propoxide, titanium isopropoxide, titanium phenoxide, zirconiumbutoxide, dibutyltin oxide, dibutyltin diacetate, tin phenoxide, tinoctylate, tin stearate, dibutyltin dioctoate, dibutyltin dioleylmaleate,dibutyltin dibutylmaleate, dibutyltin dilaurate,1,1,3,3-tetrabutyl-1,3-dilauryloxycarbonyldistannoxane,dibutyltindiacetate, dibutyltin diacetylacetonate, dibutyltinbis(o-phenylphenoxide), dibutyltin bis(triethoxysilicate), dibutyltindistearate, dibutyltin bis(isononyl-3-mercaptopropionate), dibutyltinbis(isooctyl thioglycolate), dioctyltin oxide, dioctyltin dilaurate,dioctyltin diacetate, and dioctyltin diversatate.

D. Co-Solvent

The alcoholysis reaction is typically carried out in the absence of asolvent other than the alcohol reactant. Nevertheless, a co-solvent maybe employed in some embodiments of the present invention. In oneembodiment, for instance, the co-solvent may facilitate the dispersionof the catalyst in the reactant alcohol. Examples of suitableco-solvents may include ethers, such as diethyl ether, anisole,tetrahydrofuran, ethylene glycol dimethyl ether, triethylene glycoldimethyl ether, tetraethylene glycol dimethyl ether, dioxane, etc.;alcohols, such as methanol, ethanol, n-butanol, benzyl alcohol, ethyleneglycol, diethylene glycol, etc.; phenols, such as phenol, etc.;carboxylic acids, such as formic acid, acetic acid, propionic acid,toluic acid, etc.; esters, such as methyl acetate, butyl acetate, benzylbenzoate, etc.; aromatic hydrocarbons, such as benzene, toluene,ethylbenzene, tetralin, etc.; aliphatic hydrocarbons, such as n-hexane,n-octane, cyclohexane, etc.; halogenated hydrocarbons, such asdichloromethane, trichloroethane, chlorobenzene, etc.; nitro compounds,such as nitromethane, nitrobenzene, etc.; carbamides, such asN,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc.;ureas, such as N,N-dimethylimidazolidinone, etc.; sulfones, such asdimethyl sulfone, etc.; sulfoxides, such as dimethyl sulfoxide, etc.;lactones, such as butyrolactone, caprolactone, etc.; carbonic acidesters, such as dimethyl carbonate, ethylene carbonate, etc.; and soforth.

When employed, the co-solvent(s) may be employed in an amount from about0.5 wt. % to about 20 wt. %, in some embodiments from about 0.8 wt. % toabout 10 wt. %, and in some embodiments, from about 1 wt. % to about 5wt. %, based on the weight of the reactive composition. It should beunderstood, however, that a co-solvent is not required. In fact, in someembodiments of the present invention, the reactive composition issubstantially free of any co-solvents, e.g., less than about 0.5 wt. %of the reactive composition.

E. Other Ingredients

Other ingredients may of course be utilized for a variety of differentreasons. For instance, a wetting agent may be employed in someembodiments of the present invention to improve hydrophilicity. Wettingagents suitable for use in the present invention are generallycompatible with aliphatic-aromatic copolyesters. Examples of suitablewetting agents may include surfactants, such as UNITHOX® 480 andUNITHOX® 750 ethoxylated alcohols, or UNICID™ acid amide ethoxylates,all available from Petrolite Corporation of Tulsa, Okla. Other suitablewetting agents are described in U.S. Pat. No. 6,177,193 to Tsai, et al.,which is incorporated herein in its entirety by reference thereto forall relevant purposes. Still other materials that may be used include,without limitation, melt stabilizers, processing stabilizers, heatstabilizers, light stabilizers, antioxidants, pigments, surfactants,waxes, flow promoters, plasticizers, particulates, and other materialsadded to enhance processability. When utilized, such additionalingredients are each typically present in an amount of less than about 5wt. %, in some embodiments less than about 1 wt. %, and in someembodiments, less than about 0.5 wt. %, based on the weight of thealiphatic-aromatic copolyester starting polymer.

IV. Reaction Techniques

The alcoholysis reaction may be performed using any of a variety ofknown techniques. In one embodiment, for example, the reaction isconducted while the starting polymer is in the melt phase (“meltblending”) to minimize the need for additional solvents and/or solventremoval processes. The raw materials (e.g., biodegradable polymer,alcohol, catalyst, etc.) may be supplied separately or in combination(e.g., in a solution). The raw materials may likewise be supplied eithersimultaneously or in sequence to a melt-blending device thatdispersively blends the materials. Batch and/or continuous melt blendingtechniques may be employed. For example, a mixer/kneader, Banbury mixer,Farrel continuous mixer, single-screw extruder, twin-screw extruder,roll mill, etc., may be utilized to blend the materials. Oneparticularly suitable melt-blending device is a co-rotating, twin-screwextruder (e.g., ZSK-30 twin-screw extruder available from Werner &Pfleiderer Corporation of Ramsey, N.J.). Such extruders may includefeeding and venting ports and provide high intensity distributive anddispersive mixing, which facilitate the alcoholysis reaction. The rawmaterials (e.g., polymer, alcohol, catalyst, etc.) may be fed into theextruder from a hopper. The raw materials may be provided to the hopperusing any conventional technique and in any state. For example, thealcohol may be supplied as a vapor or liquid. Alternatively, thealiphatic-aromatic copolyester may be fed to the hopper, and the alcoholand optional catalyst (either in combination or separately) may beinjected into the copolyester melt in the extruder downstream from thehopper.

Regardless of the particular melt blending technique chosen, the rawmaterials are blended under high shear/pressure and heat to ensuresufficient mixing for initiating the alcoholysis reaction. For example,melt blending may occur at a temperature of from about 50° C. to about300° C., in some embodiments, from about 70° C. to about 250° C., and insome embodiments, from about 90° C. to about 220° C. Likewise, theapparent shear rate during melt blending may range from about 100seconds⁻¹ to about 10,000 seconds⁻¹, in some embodiments from about 500seconds⁻¹ to about 5000 seconds⁻¹, and in some embodiments, from about800 seconds⁻¹ to about 1200 seconds⁻¹. The apparent shear rate is equalto 4Q/πR³, where Q is the volumetric flow rate (“m³/s”) of the polymermelt and R is the radius (“m”) of the capillary (e.g., extruder die)through which the melted polymer flows.

V. Substantially Continuous Filaments

Any of a variety of known techniques may be employed to formsubstantially continuous filaments in accordance with the presentinvention. A modified aliphatic-aromatic copolyester may be initiallyformed and then fed to an extruder in a filament formation line (e.g.,extruder 12 of a spinning line). Alternatively, the modifiedaliphatic-aromatic copolymer may be directly formed into a filament.Referring to FIG. 1, for example, one embodiment of a process 10 forforming a substantially continuous filament in accordance with thepresent invention is shown. As illustrated, the process 10 of thisembodiment is arranged to produce a bicomponent, continuous filamentweb, although it should be understood that other embodiments arecontemplated by the present invention. The process 10 employs a pair ofextruders 12 a and 12 b for separately extruding a first component A(e.g., high melting point polymer component) and a second component B(e.g., low melting point polymer component). The relative amount of thecomponents A and B may generally vary based on the desired properties.For example, the first component A normally constitutes from about 5 wt.% to about 95 wt. %, in some embodiments from about 10 wt. % to about 90wt. %, and in some embodiments, from about 15 wt. % to about 85 wt. % ofthe multicomponent filaments. Likewise, the second component B normallyconstitutes from about 5 wt. % to about 95 wt. %, in some embodimentsfrom about 10 wt. % to about 90 wt. %, and in some embodiments, fromabout 15 wt. % to about 85 wt. % of the multicomponent filaments.

The first component A is fed into the respective extruder 12 a from afirst hopper 14 a and the second component B is fed into the respectiveextruder 12 b from a second hopper 14 b. The components A and B are fedfrom the extruders 12 a and 12 b (“co-extruded”) through respectivepolymer conduits 16 a and 16 b to a spinneret 18. Spinnerets forextruding multicomponent filaments are well known to those of skill inthe art. For example, the spinneret 18 may include a housing containinga spin pack having a plurality of plates stacked one on top of eachother and having a pattern of openings arranged to create flow paths fordirecting polymer components A and B separately through the spinneret18. The spinneret 18 also has openings arranged in one or more rows. Theopenings form a downwardly extruding curtain of filaments when thepolymers are extruded therethrough. The spinneret 18 may be arranged toform sheath/core, side-by-side, pie, or other configurations.

The process 10 also employs a quench blower 20 positioned adjacent thecurtain of filaments extending from the spinneret 18. Air from thequench air blower 20 quenches the filaments extending from the spinneret18. The quench air may be directed from one side of the filament curtainas shown in FIG. 1 or both sides of the filament curtain. A fiber drawunit or aspirator 22 is positioned below the spinneret 18 and receivesthe quenched filaments. Fiber draw units or aspirators for use in meltspinning polymers are well-known in the art. Suitable fiber draw unitsfor use in the process of the present invention include a linear fiberaspirator of the type shown in U.S. Pat. Nos. 3,802,817 and 3,423,255,which are incorporated herein in their entirety by reference thereto forall relevant purposes. The fiber draw unit 22 generally includes anelongate vertical passage through which the filaments are drawn byaspirating air entering from the sides of the passage and flowingdownwardly through the passage. A heater or blower 24 suppliesaspirating air to the fiber draw unit 22. The aspirating air draws thefilaments and ambient air through the fiber draw unit 22. Thereafter,the filaments are formed into a coherent web structure by randomlydepositing the filaments onto a forming surface 26 (optionally with theaid of a vacuum) and then bonding the resulting web using any knowntechnique.

To initiate filament formation, the hoppers 14 a and 14 b are initiallyfilled with the respective components A and B. Components A and B aremelted and extruded by the respective extruders 12 a and 12 b throughpolymer conduits 16 a and 16 b and the spinneret 18. Due to therelatively low apparent viscosity of the modified aliphatic-aromaticcopolyesters used in the present invention, lower extrusion temperaturesmay be employed. For example, the extruder 12 b for Component B mayemploy one or multiple zones operating at a temperature of from about120° C. to about 200° C., and in some embodiments, from about 145° C. toabout 195° C. Likewise, the extruder 12 a for Component A may employ oneor multiple zones operating at a temperature of from about 160° C. toabout 250° C., and in some embodiments, from about 190° C. to about 225°C. Typical shear rates range from about 100 seconds⁻¹ to about 10,000seconds⁻¹, in some embodiments from about 500 seconds⁻¹ to about 5000seconds⁻¹, and in some embodiments, from about 800 seconds⁻¹ to about1200 seconds⁻¹.

As the extruded filaments extend below the spinneret 18, a stream of airfrom the quench blower 20 at least partially quenches the filaments.Such a process generally reduces the temperature of the extrudedpolymers at least about 100° C. over a relatively short time frame(seconds). This will generally reduce the temperature change needed uponcooling, to preferably be less than 150° C. and, in some cases, lessthan 100° C. The ability to use relatively low extruder temperature inthe present invention also allows for the use of lower quenchingtemperatures. For example, the quench blower 20 may employ one or morezones operating at a temperature of from about 20° C. to about 100° C.,and in some embodiments, from about 25° C. to about 60° C. Afterquenching, the filaments are drawn into the vertical passage of thefiber draw unit 22 by a flow of a gas such as air, from the heater orblower 24 through the fiber draw unit. The flow of gas causes thefilaments to draw or attenuate which increases the molecular orientationor crystallinity of the polymers forming the filaments. The filamentsare deposited through the outlet opening of the fiber draw unit 22 andonto a foraminous surface 26. Due to the high strength of the filamentsof the present invention, high draw ratios (e.g., linear speed of theforaminous surface 26 divided by the melt pump rate of the extruders 12a and 12 b) may be employed in the present invention. For example, thedraw ratio may be from about 200:1 to about 6000:1, in some embodimentsfrom about 500:1 to about 5000:1, and in some embodiments, from about1000:1 to about 4000:1.

The desired denier of the filaments may vary depending on the desiredapplication. Typically, the filaments are formed to have a denier perfilament of less than about 6, in some embodiments less than about 3,and in some embodiments, from about 0.5 to about 3. In addition, thefilaments generally have an average diameter not greater than about 100microns, in some embodiments from about 0.5 microns to about 50 microns,and in some embodiments, from about 4 microns to about 40 microns. Theability to produce such filaments may be facilitated in the presentinvention through the use of a modified copolyester having the desirablecombination of low apparent viscosity and high melt flow index.

If desired, an endless foraminous forming surface 26 may be positionedbelow the fiber draw unit 22 and receive the filaments from an outletopening. The forming surface 26 travels around guide rollers 28. Avacuum 30 positioned below the forming surface 26 to draw the filamentsagainst the forming surface 26 and consolidate the unbonded nonwovenweb. The web may then be compressed by a compression roller 32. Onceformed, the nonwoven web may be bonded using any conventional technique,such as with an adhesive or autogenously (e.g., fusion and/orself-adhesion of the filaments without an applied external adhesive).Autogenous bonding, for instance, may be achieved through contact of thefilaments while they are semi-molten or tacky, or simply by blending atackifying resin and/or solvent with the aliphatic polyester(s) used toform the filaments. Suitable autogenous bonding techniques may includeultrasonic bonding, thermal bonding, through-air bonding, and so forth.

In FIG. 1, for instance, the web passes through a nip formed between apair of rolls 34 prior to being wound onto a roll 42. One or both of therolls 34 may be heated to melt-fuse the filaments and/or containintermittently raised bond points to provide an intermittent bondingpattern. The pattern of the raised points may be selected so that thenonwoven web has a total bond area of less than about 50% (as determinedby conventional optical microscopic methods), and in some embodiments,less than about 30%. Likewise, the bond density is also typicallygreater than about 100 bonds per square inch, and in some embodiments,from about 250 to about 500 pin bonds per square inch. Such acombination of total bond area and bond density may be achieved bybonding the web with a pin bond pattern having more than about 100 pinbonds per square inch that provides a total bond surface area less thanabout 30% when fully contacting a smooth anvil roll. In someembodiments, the bond pattern may have a pin bond density from about 250to about 350 pin bonds per square inch and a total bond surface areafrom about 10% to about 25% when contacting a smooth anvil roll.Exemplary bond patterns include, for instance, those described in U.S.Pat. No. 3,855,046 to Hansen et al., U.S. Pat. No. 5,620,779 to Levy etal., U.S. Pat. No. 5,962,112 to Haynes et al., U.S. Pat. No. 6,093,665to Sayovitz et al., U.S. Design Pat. No. 428,267 to Romano et al. andU.S. Design Pat. No. 390,708 to Brown, which are incorporated herein intheir entirety by reference thereto for all purposes.

Due to the particular rheological and thermal properties of thecomponents used to form the multicomponent filaments, the web bondingconditions (e.g., temperature and nip pressure) may be selected to causethe low melting point, modified copolyester to melt and flow withoutsubstantially melting the high melting point polyester. For example, thebonding temperature (e.g., the temperature of the rollers 34) may befrom about 50° C. to about 160° C., in some embodiments from about 80°C. to about 160° C., and in some embodiments, from about 100° C. toabout 140° C. Likewise, the nip pressure may range from about 5 to about150 pounds per square inch, in some embodiments, from about 10 to about100 pounds per square inch, and in some embodiments, from about 30 toabout 60 pounds per square inch.

When bonded in this manner, the low melting point, modified copolyestermay thus form a matrix within the compacted area that substantiallysurrounds the high melting point polymer. Because the high melting pointpolymer does not substantially melt, however, it retains a substantiallyfibrous form. The high melting point polymer is also generally orientedwithin the compacted area in two or more directions due to the randommanner in which the filaments are deposited. One polymer, for instance,may be oriented from about 60° to about 120°, and in some cases, about90°, relative to another polymer within a compacted area. In thismanner, the high melting point polymer may impart enhanced strength andtoughness to the resulting web. For example, the nonwoven web mayexhibit a relatively high “peak load”, which indicates the maximum loadto break as expressed in units of grams-force per inch. The MD peak loadof the web may, for instance, be at least about 3000 grams-force perinch (“g_(f)/in”), in some embodiments at least about 3500 g_(f)/in, andin some embodiments, at least about 4000 g_(f)/in. The CD peak load mayalso be at least about 1200 grams-force per inch (“g_(f)/in”), in someembodiments at least about 1500 g_(f)/in, and in some embodiments, atleast about 2500 g_(f)/in.

In addition to contributing to the overall strength of the web, theselected bond conditions may also improve other mechanical properties ofthe web. For example, although retaining its fiber form within acompacted area, the high melting point polymer will normally release orseparate from the compacted area upon the application of strain, ratherthan fracture. By releasing under strain, the polymer may continue tofunction as a load bearing member even after the web has exhibitedsubstantial elongation. In this regard, the nonwoven web is capable ofexhibiting improved “peak elongation” properties, i.e., the percentelongation of the web at its peak load. For example, the nonwoven webmay exhibit a machine direction (“MD”) peak elongation of at least about10%, in some embodiments at least about 20%, and in some embodiments, atleast about 35%. The nonwoven web may also exhibit a cross-machinedirection (“CD”) peak elongation of at least about 35%, in someembodiments at least about 45%, and in some embodiments, at least about50%. Of course, in addition to possessing good mechanical properties,the nonwoven web is also soft, drapable, and tactile. Further, thenonwoven web possesses good water absorption characteristics, whichfacilitates its ability to be used in absorbent articles.

The filaments of the present invention may constitute the entire fibrouscomponent of the nonwoven web or blended with other types of fibers(e.g., staple fibers, continuous filaments, etc). When blended withother types of fibers, it is normally desired that the filaments of thepresent invention constitute from about 20 wt % to about 95 wt. %, insome embodiments from about 30 wt. % to about 90 wt. %, and in someembodiments, from about 40 wt. % to about 80 wt. % of the total amountof fibers employed in the nonwoven web. For example, additionalmonocomponent and/or multicomponent synthetic fibers may be utilized inthe nonwoven web. Some suitable polymers that may be used to form thesynthetic fibers include, but are not limited to: polyolefins, e.g.,polyethylene, polypropylene, polybutylene, and so forth;polytetrafluoroethylene; polyesters, e.g., polyethylene terephthalateand so forth; polyvinyl acetate; polyvinyl chloride acetate; polyvinylbutyral; acrylic resins, e.g., polyacrylate, polymethylacrylate,polymethylmethacrylate, and so forth; polyamides, e.g., nylon; polyvinylchloride; polyvinylidene chloride; polystyrene; polyvinyl alcohol;polyurethanes; polylactic acid; etc. If desired, biodegradable polymers,such as poly(glycolic acid) (PGA), polylactic acid) (PLA), poly(β-malicacid) (PMLA), poly(s-caprolactone) (PCL), poly(p-dioxanone) (PDS),poly(butylene succinate) (PBS), and poly(3-hydroxybutyrate) (PHB), mayalso be employed. Some examples of known synthetic fibers includesheath-core bicomponent fibers available from KoSa Inc. of Charlotte,N.C. under the designations T-255 and 1-256, both of which use apolyolefin sheath, or T-254, which has a low melt co-polyester sheath.Still other known bicomponent fibers that may be used include thoseavailable from the Chisso Corporation of Moriyama, Japan or FibervisionsLLC of Wilmington, Del. Synthetic or natural cellulosic polymers mayalso be used, including but not limited to, cellulosic esters;cellulosic ethers; cellulosic nitrates; cellulosic acetates; cellulosicacetate butyrates; ethyl cellulose; regenerated celluloses, such asviscose, rayon, and so forth.

The filaments of the present invention may also be blended with pulpfibers, such as high-average fiber length pulp, low-average fiber lengthpulp, or mixtures thereof. One example of suitable high-average lengthfluff pulp fibers includes softwood kraft pulp fibers. Softwood kraftpulp fibers are derived from coniferous trees and include pulp fiberssuch as, but not limited to, northern, western, and southern softwoodspecies, including redwood, red cedar, hemlock, Douglas fir, true firs,pine (e.g., southern pines), spruce (e.g., black spruce), combinationsthereof, and so forth. Northern softwood kraft pulp fibers may be usedin the present invention. An example of commercially available southernsoftwood kraft pulp fibers suitable for use in the present inventioninclude those available from Weyerhaeuser Company with offices inFederal Way, Wash. under the trade designation of “NB-416.” Anothersuitable pulp for use in the present invention is a bleached, sulfatewood pulp containing primarily softwood fibers that is available fromBowater Corp. with offices in Greenville, S.C. under the trade nameCoosAbsorb S pulp. Low-average length fibers may also be used in thepresent invention. An example of suitable low-average length pulp fibersis hardwood kraft pulp fibers. Hardwood kraft pulp fibers are derivedfrom deciduous trees and include pulp fibers such as, but not limitedto, eucalyptus, maple, birch, aspen, etc. Eucalyptus kraft pulp fibersmay be particularly desired to increase softness, enhance brightness,increase opacity, and change the pore structure of the sheet to increaseits wicking ability.

Nonwoven laminates may also be formed in which one or more layers areformed from the multicomponent filaments of the present invention. Inone embodiment, for example, the nonwoven laminate contains a meltblownlayer positioned between two spunbond layers to form aspunbond/meltblown/spunbond (“SMS”) laminate. If desired, one or more ofthe spunbond layers may be formed from the filaments of the presentinvention. The meltblown layer may be formed from the modifiedcopolyester, other biodegradable polymer(s), and/or any other polymer(e.g., polyolefins). Various techniques for forming SMS laminates aredescribed in U.S. Pat. Nos. 4,041,203 to Brock et al.; 5,213,881 toTimmons, et al.; 5,464,688 to Timmons, et al.; 4,374,888 to Bornslaeger;5,169,706 to Collier, et al.; and 4,766,029 to Brock et al., as well asU.S. Patent Application Publication No. 2004/0002273 to Fitting, et al.,all of which are incorporated herein in their entirety by referencethereto for all purposes. Of course, the nonwoven laminate may haveother configuration and possess any desired number of meltblown andspunbond layers, such as spunbond/meltblown/meltblown/spunbond laminates(“SMMS”), spunbond/meltblown laminates (“SM”), etc. Although the basisweight of the nonwoven laminate may be tailored to the desiredapplication, it generally ranges from about 10 to about 300 grams persquare meter (“gsm”), in some embodiments from about 25 to about 200gsm, and in some embodiments, from about 40 to about 150 gsm.

If desired, the nonwoven web or laminate may be applied with varioustreatments to impart desirable characteristics. For example, the web maybe treated with liquid-repellency additives, antistatic agents,surfactants, colorants, antifogging agents, fluorochemical blood oralcohol repellents, lubricants, and/or antimicrobial agents. Inaddition, the web may be subjected to an electret treatment that impartsan electrostatic charge to improve filtration efficiency. The charge mayinclude layers of positive or negative charges trapped at or near thesurface of the polymer, or charge clouds stored in the bulk of thepolymer. The charge may also include polarization charges that arefrozen in alignment of the dipoles of the molecules. Techniques forsubjecting a fabric to an electret treatment are well known by thoseskilled in the art. Examples of such techniques include, but are notlimited to, thermal, liquid-contact, electron beam and corona dischargetechniques. In one particular embodiment, the electret treatment is acorona discharge technique, which involves subjecting the laminate to apair of electrical fields that have opposite polarities. Other methodsfor forming an electret material are described in U.S. Pat. Nos.4,215,682 to Kubik. et al.; 4,375,718 to Wadsworth; 4,592,815 to Nakao;4,874,659 to Ando; 5,401,446 to Tsai, et al.; 5,883,026 to Reader, etal.; 5,908,598 to Rousseau, et al.; 6,365,088 to Knight, et al., whichare incorporated herein in their entirety by reference thereto for allpurposes.

The nonwoven web or laminate may be used in a wide variety ofapplications. For example, the web may be incorporated into a “medicalproduct”, such as gowns, surgical drapes, facemasks, head coverings,surgical caps, shoe coverings, sterilization wraps, warming blankets,heating pads, and so forth. Of course, the nonwoven web may also be usedin various other articles. For example, the nonwoven web may beincorporated into an “absorbent article” that is capable of absorbingwater or other fluids. Examples of some absorbent articles include, butare not limited to, personal care absorbent articles, such as diapers,training pants, absorbent underpants, incontinence articles, femininehygiene products (e.g., sanitary napkins), swim wear, baby wipes, mittwipe, and so forth; medical absorbent articles, such as garments,fenestration materials, underpads, bedpads, bandages, absorbent drapes,and medical wipes; food service wipers; clothing articles; pouches, andso forth. Materials and processes suitable for forming such articles arewell known to those skilled in the art. Absorbent articles, forinstance, typically include a substantially liquid-impermeable layer(e.g., outer cover), a liquid-permeable layer (e.g., bodyside liner,surge layer, etc.), and an absorbent core. In one embodiment, forexample, a nonwoven web formed according to the present invention may beused to form an outer cover of an absorbent article. If desired, thenonwoven web may be laminated to a liquid-impermeable film that iseither vapor-permeable or vapor-impermeable.

The present invention may be better understood with reference to thefollowing examples.

Test Methods

Molecular Weight:

The molecular weight distribution of a polymer was determined by gelpermeation chromatography (“GPC”). The samples were initially preparedby adding 0.5% wt/v solutions of the sample polymers in chloroform to40-milliliter glass vials. For example, 0.05±0.0005 grams of the polymerwas added to 10 milliliters of chloroform. The prepared samples wereplaced on an orbital shaker and agitated overnight. The dissolved samplewas filtered through a 0.45-micrometer PTFE membrane and analyzed usingthe following conditions:

-   Columns: Styragel HR 1, 2, 3, 4, & 5E (5 in series) at 41° C.-   Solvent/Eluent: Chloroform @1.0 milliliter per minute-   HPLC: Waters 600E gradient pump and controller, Waters 717 auto    sampler-   Detector: Waters 2414 Differential Refractometer at sensitivity=30,    at 40° C. and scale factor of 20-   Sample Concentration; 0.5% of polymer “as is”-   Injection Volume: 50 microliters-   Calibration Standards Narrow MW polystyrene, 30-microliter injected    volume.

Number Average Molecular Weight (MW_(n)), Weight Average MolecularWeight (MW_(w)) and first moment of viscosity average molecular weight(MW_(z)) were obtained.

Apparent Viscosity:

The rheological properties of polymer samples were determined using aGöttfert Rheograph 2003 capillary rheometer with WinRHEO version 2.31analysis software. The setup included a 2000-bar pressure transducer anda 30/1:0/180 roundhole capillary die. Sample loading was done byalternating between sample addition and packing with a ramrod. A2-minute melt time preceded each test to allow the polymer to completelymelt at the test temperature (usually 160 to 220° C.). The capillaryrheometer determined the apparent viscosity (Pa·s) at various shearrates, such as 100, 200, 500, 1000, 2000, and 4000 s⁻¹. The resultantrheology curve of apparent shear rate versus apparent viscosity gave anindication of how the polymer would run at that temperature in anextrusion process.

Melt Flow Index:

The melt flow index is the weight of a polymer (in grams) forced throughan extrusion rheometer orifice (0.0825-inch diameter) when subjected toa load of 2160 grams in 10 minutes, typically at 190° C. Unlessotherwise indicated, the melt flow index was measured in accordance withASTM Test Method D1238-E.

Thermal Properties:

The melting temperature (“T_(m)”), glass transition temperature(“T_(g)”), and latent heat of fusion (“ΔH_(f)”) were determined bydifferential scanning calorimetry (DSC). The differential scanningcalorimeter was a THERMAL ANALYST 2910 Differential Scanningcalorimeter, which was outfitted with a liquid nitrogen coolingaccessory and with a THERMAL ANALYST 2200 (version 8.10) analysissoftware program, both of which are available from T.A. Instruments Inc.of New Castle, Del. To avoid directly handling the samples, tweezers orother tools were used. The samples were placed into an aluminum pan andweighed to an accuracy of 0.01 milligram on an analytical balance. A lidwas crimped over the material sample onto the pan. Typically, the resinpellets were placed directly in the weighing pan, and the fibers werecut to accommodate placement on the weighing pan and covering by thelid.

The differential scanning calorimeter was calibrated using an indiummetal standard and a baseline correction was performed, as described inthe operating manual for the differential scanning calorimeter. Amaterial sample was placed into the test chamber of the differentialscanning calorimeter for testing, and an empty pan is used as areference. All testing was run with a 55-cubic centimeter per minutenitrogen (industrial grade) purge on the test chamber. For resin pelletsamples, the heating and cooling program was a 2-cycle test that beganwith an equilibration of the chamber to −50° C., followed by a firstheating period at a heating rate of 10° C. per minute to a temperatureof 200° C., followed by equilibration of the sample at 200° C. for 3minutes, followed by a first cooling period at a cooling rate of 10° C.per minute to a temperature of −50° C., followed by equilibration of thesample at −50° C. for 3 minutes, and then a second heating period at aheating rate of 10° C. per minute to a temperature of 200° C. For fibersamples, the heating and cooling program was a 1-cycle test that beganwith an equilibration of the chamber to −50° C., followed by a heatingperiod at a heating rate of 10° C. per minute to a temperature of 200°C., followed by equilibration of the sample at 200° C. for 3 minutes,and then a cooling period at a cooling rate of 10° C. per minute to atemperature of −50° C. All testing was run with a 55-cubic centimeterper minute nitrogen (industrial grade) purge on the test chamber.

The results were then evaluated using the THERMAL ANALYST 2200 (version8.10) analysis software program, which identified and quantified theglass transition temperature of inflection, the endothermic andexothermic peaks, and the areas under the peaks on the DSC plots. Theglass transition temperature was identified as the region on theplot-line where a distinct change in slope occurred, and the meltingtemperature was determined using an automatic inflection calculation.The areas under the peaks on the DSC plots were determined in terms ofjoules per gram of sample (J/g). For example, the heat of fusion of aresin or fiber sample was determined by integrating the area of theendothermic peak. The area values were determined by converting theareas under the DSC plots (e.g. the area of the endotherm) into theunits of joules per gram (Jig) using computer software.

Fiber Tenacity:

Individual fiber specimens were carefully extracted from an unbondedportion of a fiber web in a manner that did not significantly pull onthe fibers. These fiber specimens were shortened (e.g. cut withscissors) to 38 millimeters in length, and placed separately on a blackvelvet cloth. 10 to 15 fiber specimens were collected in this manner.The fiber specimens were then mounted in a substantially straightcondition on a rectangular paper frame having external dimension of 51millimeters×51 millimeters and internal dimension of 25 millimeters×25millimeters. The ends of each fiber specimen were operatively attachedto the frame by carefully securing the fiber ends to the sides of theframe with adhesive tape. Each fiber specimen was then be measured forits external, relatively shorter, cross-fiber dimension employing aconventional laboratory microscope, which has been properly calibratedand set at 40× magnification. This cross-fiber dimension was recorded asthe diameter of the individual fiber specimen. The frame helped to mountthe ends of the sample fiber specimens in the upper and lower grips of aconstant rate of extension type tensile tester in a manner that avoidedexcessive damage to the fiber specimens.

A constant rate of extension type of tensile tester and an appropriateload cell were employed for the testing. The load cell was chosen (e.g.10N) so that the test value fell within 10-90% of the full scale load.The tensile tester (i.e., MTS SYNERGY 200) and load cell were obtainedfrom MTS Systems Corporation of Eden Prairie, Mich. The fiber specimensin the frame assembly were then mounted between the grips of the tensiletester such that the ends of the fibers were operatively held by thegrips of the tensile tester. Then, the sides of the paper frame thatextended parallel to the fiber length were cut or otherwise separated sothat the tensile tester applied the test force only to the fibers. Thefibers were then subjected to a pull test at a pull rate and grip speedof 12 inches per minute. The resulting data was analyzed using aTESTWORKS 4 software program from the MTS Corporation with the followingtest settings:

Calculation Inputs Test Inputs Break mark drop   50% Break sensitivity90% Break marker elongation 0.1 in Break threshold  10 g_(f) Nominalgage length   1 in Data Acq, Rate  10 Hz Slack pre-load   1 lb_(f)Denier length 9000 m Slope segment length   20% Density  1.25 g/cm³Yield offset 0.20% Initial speed  12 in/min Yield segment length   2%Secondary speed   2 in/min

The tenacity values were expressed in terms of gram-force per denier.

Example 1

An aliphatic-aromatic copolyester resin was initially obtained from BASFunder the designation ECOFLEX® F BX 7011. The copolyester resin wasmodified by melt blending with a reactant solution. For Samples 1 and 4(see Table 1), the reactant solution contained 89 wt. % 1,4-butanedioland 11 wt. % acetone. For Samples 2, 3, 5, and 6 (see Table 1), thereactant solution contained 87 wt. % 1,4-butanediol, 11 wt. % acetone,and 2 wt. % dibutyltin diacetate (the catalyst). The solution was fed byan Eldex pump to a liquid injection port located at barrel #4 of aco-rotating, twin-screw extruder (USALAB Prism H16, diameter: 16 mm, L/Dof 40/1) manufactured by Thermo Electron Corporation. The resin was fedto the twin screw extruder at barrel #1. The screw length was 25 inches.The extruder had one die opening having a diameter of 3 millimeters.Upon formation, the extruded resin was cooled on a fan-cooled conveyorbelt and formed into pellets by a Conair pelletizer. Reactive extrusionparameters were monitored on the USALAB Prism H16 extruder during thereactive extrusion process. The conditions are shown below in Table 1.

TABLE 1 Reactive Extrusion Process Conditions for modifying Ecoflex F BX7011 on a USALAB Prism H16 Sample Temperature (° C.) Screw Speed ResinRate Reactant No. Zone 1, 2, 3-8, 9, 10 (rpm) (lb/h) (% of resin rate) FBX 7011 90 125 165 125 110 150 2.6 0 1 90 125 165 125 110 150 2.6 4 (Nocatalyst) 2 90 125 165 125 110 150 2.6 4 3 90 125 180 125 110 150 2.6 44 90 125 190 125 110 150 2.6 4 (No catalyst) 5 90 125 190 125 110 1502.6 4 6 90 125 200 125 110 150 2.6 4

The melt rheology was studied for the unmodified ECOFLEX® F BX 7011 andSamples 1-6 (modified with 1,4 butanediol). The measurement was carriedout on a Göettfert Rheograph 2003 (available from Göettfert of RockHill, S.C.) at 170° C. with a 30/1 (Length/Diameter) mm/mm die. Theapparent melt viscosity was determined at apparent shear rates of 100,200, 500, 1000, 2000 and 5000 s⁻¹. The apparent melt viscosities at thevarious apparent shear rates were plotted and the rheology curves weregenerated as shown in FIG. 2. As illustrated, the apparent viscosity ofthe control sample (unmodified ECOFLEX® resin) was much higher than theapparent viscosities of Samples 1-6. The melt flow indices of thesamples were also determined with a Tinius Olsen Extrusion plastometer(170° C., 2.16 kg). Further, the samples were subjected to molecularweight (MW) analysis by GPC with narrow MW distribution polystyrenes asstandards. The results are set forth below in Table 2.

TABLE 2 Properties of modified Ecoflex F BX 7011 on a USALAB Prism H16Apparent Viscosity Melt Flow (Pa · s at rate apparent (g/10 min AverageMol. Poly- Sample shear rate at 170° C. Wt (g/mol) dispersity No. of1000/s) and 2.16 kg) Mw Mn (Mw/Mn) F BX 7011 498 1.65 125206 73548 1.7 1365 9.6 114266 67937 1.68 2 51 230 77391 41544 1.86 3 37 377 71072 397671.79 4 241 14 109317 66507 1.64 5 38 475 65899 35529 1.85 6 22 571 5680929316 1.94

As indicated, the melt flow indices of the modified resins (Samples 1-6)were significantly greater than the control sample. In addition, theweight average molecular weight (M_(w)) and number average molecularweight (M_(n)) were decreased in a controlled fashion, which confirmedthat the increase in melt flow index was due to alcoholysis withbutanediol. The resulting modified aliphatic-aromatic copolyesters hadhydroxybutyl terminal groups.

Example 2

The modification of ECOFLEX® F BX 7011 by monohydric alcohols wasdemonstrated with 1-butanol, 2-propanol, and 2-ethoxy-ethanol asexamples of monohydric alcohols. The experimental set-up was the same asdescribed in Example 1. The process conditions are shown in Table 3.Dibutyltin diacetate was the catalyst used. As shown in Table 3, thetorque decreased as monohydric alcohol was fed to the extruder. Thetorque was further decreased as monohydric alcohol and catalyst wereboth fed to the extruder.

TABLE 3 Reactive Extrusion Conditions for modifying Ecoflex F BX 7011 ona USALAB Prism H16 with monohydric alcohols Sample Temperature ( ° C.)Screw Speed Resin Rate Reactant Catalyst Torque I.D. Zone 1, 2, 3-8, 9,10 (rpm) (lb/h) (% of resin rate) (% of resin rate) (%) F BX 7011 90 125180 125 110 150 2.5 0 0 >100 7 90 125 180 125 110 150 2.5 3.4%,2-Propanol 0 90 8 90 125 180 125 110 150 2.5 3.4%, 2-Propanol 0.1 80 990 125 180 125 110 150 2.5 3.6%, 1-Butanol 0 72 10 90 125 180 125 110150 2.5 3.6%, 1-Butanol 0.1 54 11 90 125 180 125 110 150 2.5 4%,2-Ethoxy-ethanol 0 64 12 90 125 180 125 110 150 2.5 4%, 2-Ethoxy-ethanol0.1 58

The apparent viscosity and molecular weight were determined for eachsample as described in Example 1. The results are shown below in Table4.

TABLE 4 Properties of modified Ecoflex F BX 7011 with monohydricalcohols on a USALAB Prism H16 Apparent Viscosity (Pa · s at AverageMol. Sample apparent shear Wt (g/mol) Polydispersity I.D. rate of 10001/s) Mw Mn (Mw/Mn) F BX 7011 376 128100 77200 1.66  7 364 120800 718001.68  8 273 115000 69400 1.66  9 292 115900 70800 1.64 10 126 8980051000 1.76 11 324 116800 71000 1.64 12 215 104100 60500 1.72

As indicated, Samples 7-12 had lower apparent viscosities and molecularweights over the entire range of shear rates than the control sample.The resulting modified copolyesters had alkyl terminal groups that arecompositionally different than the unmodified copolyester.

Example 3

Modification of ECOFLEX® F BX 7011 with 1,4-butanediol was performed asdescribed in Example 1 using titanium propoxide (“Ti-P”), titaniumbutoxide (“Ti-B”) and titanium isopropoxide (“Ti-IsoP”) catalysts.During the reactive extrusion process, the torques of the extruder weremoderately decreased with the addition of only 1,4-butanediol, andfurther decreased with the addition of the titanium catalysts. Theprocess conditions are shown in Table 5. The resulting modifiedcopolyesters have hydroxybutyl terminal groups.

TABLE 5 Reactive Extrusion Process Conditions for modifying Ecoflex F BX7011 on a USALAB Prism H16 with 1,4-butanediol and titanium catalystsSample Temperature ( ° C.) Screw Speed Resin Rate 1,4-butanediolCatalyst Torque I.D. Zone 1, 2, 3-8, 9, 10 (rpm) (lb/h) (% of resinrate) (ppm of resin rate) (%) F BX 7011 95 145 180 130 100 150 3 00 >100 13 95 145 180 130 100 150 3 2 0 85 14 95 145 180 130 100 150 33.5 0 75 15 95 145 180 130 100 150 3 2 400, TI-P 69 16 95 145 180 130100 150 3 3.5 700, Ti-P 48 17 95 145 180 130 100 150 3 2 400, Ti-B 76 1895 145 180 130 100 150 3 3.5 700, Ti-B 55 19 95 145 180 130 100 150 3 2400, Ti-IsoP 79 20 95 145 180 130 100 150 3 3.5 700, Ti-IsoP 64

The apparent viscosity and molecular weight were determined for eachsample as described in Example 1. The results are shown in FIG. 3 andTable 6.

TABLE 6 Properties of modified Ecoflex F BX 7011 with monohydricalcohols on a USALAB Prism H16 Apparent Viscosity (Pa · s at AverageMol. Sample apparent shear Wt (g/mol) Polydispersity I.D. rate of 10001/s) Mw Mn (Mw/Mn) F BX 7011 376 128100 77200 1.66 13 297 112800 710001.7 14 219 102000 60100 1.83 15 198 97050 57050 1.74 16 60 69100 376001.67 17 218 103700 61800 1.6 18 95 89900 51600 1.7 19 243 110200 641001.68 20 87 100300 59900 1.72

As shown in FIG. 3, the viscosity of Sample 16 (titanium propoxidecatalyst) was significant lower than Sample 14 (no catalyst) over theentire range of shear rates. In addition, the molecular weights ofSamples 13-20 were less than the control sample.

Example 4

An aliphatic-aromatic copolyester resin was obtained from BASF under thedesignation ECOFLEX® F BX 7011. A reactant solution contained 87.5 wt. %1,4-butanediol, 7.5 wt. % ethanol, and 5 wt. % titanium propoxide wasmade. A co-rotating, twin-screw extruder was employed (ZSK-30, diameterof 30 millimeters) that was manufactured by Werner and PfleidererCorporation of Ramsey, N.J. The screw length was 1328 millimeters. Theextruder had 14 barrels, numbered consecutively 1-14 from the feedhopper to the die. The first barrel (#1) received the ECOFLEX® F BX 7011resin via a volumetric feeder at a throughput of 30 pounds per hour. Thefifth barrel (#5) received the reactant solution via a pressurizedinjector connected with an Eldex pump at a final rate of 0 to 1 wt. %1,4-butanediol and 0 to 700 parts per million (“ppm”) titaniumpropoxide, respectively. The screw speed was 150 revolutions per minute(“rpm”). The die used to extrude the resin had 4 die openings (6millimeters in diameter) that were separated by 3 millimeters. Uponformation, the extruded resin was cooled on a fan-cooled conveyor beltand formed into pellets by a Conair pelletizer. Reactive extrusionparameters were monitored during the reactive extrusion process. Theconditions are shown below in Table 7.

TABLE 7 Process Conditions for Reactive Extrusion of Ecoflex F BX 7011with 1,4-Butanediol on a ZSK-30 Extruder Resin Reactants ExtruderSamples feeding rate Butanediol Titanium speed Extruder temperatureprofile (° C.) Torque No. (lb/h) (%) Propoxide (ppm) (rpm) T₁ T₂ T₃ T₄T₅ T₆ T₇ T_(melt) P_(melt) (%) F BX 7011 30 0 0 150 160 170 185 185 185185 100 116 400 >100 21 30 1 0 150 160 171 184 185 185 185 100 108300 >100 22 30 0.75 375 150 160 170 185 185 185 185 100 110 70 85-90 2330 1 700 150 160 170 185 185 185 185 100 110 30 66-72

As indicated, the addition of 1 wt. % butanediol alone (Sample 21) didnot significantly decrease the torque of the control sample, althoughthe die pressure did drop from 300 to 130 pounds per square inch(“psi”). With the addition of 1 wt. % 1,4-butanediol and 700 ppmtitanium propoxide (Sample 23), both the torque and die pressuredecreased significantly to 66-72% and 30 psi, respectively. The torqueand die pressure could be proportionally adjusted with the change ofreactant and catalyst.

Melt rheology tests were also performed with the control sample andSamples 21-23 on a Göettfert Rheograph 2003 (available from Göettfert inRock Hill, S.C.) at 180° C. and 190° C. with 30/1 (Length/Diameter)mm/mm die. The apparent melt viscosity was determined at apparent shearrates of 100, 200, 500, 1000, 2000 and 4000 s⁻¹. The results are shownin FIG. 4. As indicated, Samples 21-23 had much lower apparentviscosities over the entire range of shear rates than the controlsample. The melt flow index of the sample was determined by the methodof ASTM D1239, with a Tinius Olsen Extrusion Plastometer at 190° C. and2.16 kg. Further, the samples were subjected to molecular weight (MW)analysis by GPC with narrow MW polystyrenes as standards. The resultsare set forth below in Table 8.

TABLE 8 Properties of unmodified and modified Ecoflex F BX 7011 on aZSK-30 Apparent Viscosity (Pa · s Melt at apparent Flow rate shear rate(g/10 min Average Mol. Poly- Sample of 1000/s at at 190° C. Wt (g/mol)dispersity No. 180° C.) and 2.16 kg) Mw Mn (Mw/Mn) F BX 7011 321 4.5125200 73500 1.7 Control 294 6.8 117900 72100 1.64 21 182 24 10040060500 1.66 22 112 68 82800 46600 1.78 23 61 169 68900 37600 1.83

As indicated, the melt flow indices of the modified resins (Samples21-23) were significantly greater than the control sample. In addition,the weight average molecular weight (M_(w)) and number average molecularweight (M_(n)) were decreased in a controlled fashion, which confirmedthat the increase in melt flow index was due to alcoholysis withbutanediol catalyzed. Table 9, which is set forth below, also lists thedata from DSC analysis of the control sample and Samples 21-23.

TABLE 9 DSC Analysis Glass transition Melting Peak Enthalpy temperature,T_(g) Temperature, T_(m) of melting Sample (° C.) (° C.) (J/g) Ecoflex ®F BX 7011 −30.1 123.3 11.7 Control −31.5 123.5 10.1 21 −35.1 127 10.7 22−32.5 124.7 11.6 23 −34.2 125.1 12

As indicated, Samples 22 and 23 (modified with 1,4-butanediol) exhibitedlittle change in their T_(g) and T_(m) compared with the controlsamples.

Example 5

As described in Example 4, a ZSK-30 extruder was used to form varioussamples (Samples 24-28). For Sample 24, the first barrel (#1) received90 wt. % ECOFLEX® F BX 7011 resin via a volumetric feeder, and theseventh barrel (#7) received 10 wt. % boron nitride via a side feeder,at a total throughput of 20 pounds per hour. For Sample 25, the firstbarrel (#1) received 80 wt. % ECOFLEX® F BX 7011 resin and 20% EnPol®polybutylene succinate G-4500 via two volumetric feeders, at a totalthroughput of 20 pounds per hour. For Sample 26, the first barrel (#1)received 90 wt. % ECOFLEX® F BX 7011 resin and 10 wt. % ENMAT®polyhydroxybutyrate-co-valerate via two volumetric feeders, at a totalthroughput of 30 pounds per hour. For Sample 27, the first barrel (#1)received 85 wt % ECOFLEX® F BX 7011 resin and 10 wt. % Biomer®polyhydroxybutyrate P-226 via two volumetric feeders, and seventh barrel(#7) received 5% (w/w) boron nitride via a side feeder, at a totalthroughput of 20 pounds per hour. Finally, for Sample 28, the firstbarrel (#1) received 90 wt. % ECOFLEX® F BX 7011 resin and 10 wt. %Sample 27 via two volumetric feeders at a total throughput of 30 lb/h,and the fifth barrel (#5) received a reactant solution via a pressurizedinjector connected with an Eldex pump at a final rate of 0.5 wt. %1,4-butanediol and 350 parts per million (“ppm”) titanium propoxide,respectively.

The die used to extrude the resins had 4 die openings (6 millimeters indiameter) that were separated by 3 millimeters. Upon formation, theextruded resin was cooled on a fan-cooled conveyor belt and formed intopellets by a Conair pelletizer. Reactive extrusion parameters weremonitored and recorded. The conditions are shown below in Table 10.

TABLE 10 Process Conditions on a ZSK-30 Extruder Resin ReactantsExtruder Samples feeding rate Butanediol Titanium speed Extrudertemperature profile ( ° C.) Torque No. (lb/h) (%) Propoxide (ppm) (rpm)T₁ T₂ T₃ T₄ T₅ T₆ T₇ T_(melt) P_(melt) (%) 24 20 N/A N/A 150 150 160 180180 180 175 170 192 120 95 25 20 N/A N/A 150 150 155 170 170 170 170 160180 220 85 26 30 N/A N/A 150 150 180 180 185 180 180 165 181 95 75 27 20N/A N/A 160 130 180 180 180 180 180 115 127 180 90 28 30 0.5 350 160 150190 190 190 190 190 125 137 70 88

Example 6

As described in Example 1, a USALAB Prism H16 extruder was used toprepare various samples (Samples 29-32) for evaluating their fiberspinning capacity. For Sample 29, ECOFLEX® F BX 7011 resin was fed intoextruder at Barrel #1, and a reactant solution of 2.7 wt. % of1,4-butanediol and 700 ppm of titanium propoxide (TP) was injected intothe extruder by an Eldex pump via a liquid injection port located atBarrel #4, at a total throughput of 3 pounds per hour. For Sample 30,ECOFLEX® F BX 7011 resin was fed into the extruder at Barrel #1 and areactant solution of 2.7 wt. % of 1-butanol and 700 ppm of dibutylenediacetate (DBDA) was injected into the extruder by an Eldex pump via aliquid injection port located at barrel #4, at a total throughput of 3pounds per hour. For Sample 31, a dry blend of 90 wt. % ECOFLEX® F BX7011 and 10 wt. % Sample 24 was fed into the extruder at Barrel #1, anda reactant solution of 2.7 wt. % of 1,4-butanediol and 700 ppm ofdibutylene diacetate (DBDA) was injected into the extruder by an Eldexpump via a liquid injection port located at Barrel #4, at a totalthroughput of 3 pounds per hour. For Sample 32, a dry blend of 90 wt. %ECOFLEX® F BX 7011 and 10 wt. % Sample 26 was fed into the extruder atBarrel #1, and a reactant solution of 2.7 wt. % of 1,4-butanediol and700 ppm of dibutylene diacetate (DBDA) was injected into extruder by anEldex pump via a liquid injection port located at Barrel #4, at a totalthroughput of 3 pounds per hour. The extruder profiles were monitoredand recorded. The conditions are shown below in Table 11.

TABLE 11 Reactive extrusion process conditions for producing modifiedEcoflex BFX 7011 Sample Temperature (° C.) Screw Speed Resin RateReactant Catalyst Torque I.D. Zone 1, 2, 3-8, 9, 10 (rpm) (lb/h) % ofresin rate (ppm) (%) 29 95 125 180 125 100 150 3 2.7%, 1,4-butanediol700, DBDA 64 30 95 125 180 125 100 150 3 2.7%, 1-butanol 700, DBDA 61 3195 125 180 125 100 150 3 2.7%, 1,4-butanediol 700, DBDA 59 32 95 125 180125 100 150 3 2.7%, 1,4-butanediol 700, TP 64

Example 7

Fiber spinning was conducted with a pilot Davis Standard fiber spinningline consisting of two extruders, a quench chamber and a godet with amaximal speed of 3000 m/min. The spinning die plate used for thesesamples was a 16 holes plate with each hole with a diameter of 0.6 mm.Sample 29-32 were pre-dried at 70° C. before fiber spinning. UnmodifiedEcoflex® F BX 7011 was also spun at an extruder speed of 5 rpm and 150°C. Extruder pressure rose quickly above 3650 psi and shut off. No fiberwas collected. Unmodified Ecoflex® F BX 7011 preblended with 20% PBS(Sample 25) was also spun at an extruder speed of 5 rpm, pressure of2500 psi and temperature of 160° C. Fibers could only be drawn up to 200m/min before break up. Fiber samples were analyzed on a MTS Synergie 200tensile tester. The fiber spinning conditions and resulting fiberproperties are shown in Table 12.

TABLE 12 Fiber spinning conditions and fibers properties of modifiedEcoflex resins Godet Ext. Ext. Ext. Spin Die Peak Peak Strain at Samplesspeed Temp speed press. Temp Diameter Load Stress Break No. m/min ° C.rpm Psi ° C. micron gf Mpa % Denier Tenacity 29 1500 145 10 2225 13524.3 4.12 88 104 5.3 0.8 30 1500 160 5 1300 160 16.8 2.4 105.4 103.1 2.50.96 31 2200 150 5 990 150 12.8 1.47 112.3 29.5 1.45 1.02 32 1500 160 102060 150 24.9 4.48 89.6 166.2 5.51 0.81

Example 8

Bicomponent fibers with modified Ecoflex® F BX 7011 (Sample 28) assheath and NatureWorks PLA 6201D as the core were also spun using thefiber spinning line of Example 7. The sheath/core ratios of theresulting bicomponent fibers for Sample 33 and Sample 34 were 20/80 and30/70, respectively. Fiber spinning conditions are listed in Table 13.

TABLE 13 Fiber spinning conditions for making modified Ecoflex/PLAbicomponent fibers Temperature (° C.) Pressure Melt Pump Zone 1 Zone 2Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Psi rpm Extruder 1 160 170 170 180180 180 180 140 1-1.5 Extruder 2 195 205 215 220 220 225 225 1053.5-4    Lower SP Upper SP Chimney Spinbeam Quench Setpoints (° C.) / /100 240 Lower Mid-Lower Mid-Upper Upper Lower Air Upper Air QuenchReadings (° C.) 25 28 27 28 390 432 Godet Speed (m/min) 2500

The resulting fibers were analyzed on a MTS Synergie 200 tensile tester.The properties are listed as in Table 14.

TABLE 14 Properties of modified Ecoflex and PLA bicomponent fibersSamples Sheath Core Diamter (micron) Peak load (gf) Peak Stress (Mpa)Strain at Break (%) Denier Tenacity No. (%) (%) Mean SD Mean SD Mean SDMean SD Mean SD Mean SD 33 20 80 10.5 1 2.1 0.2 242 49 67.2 12.4 0.980.19 2.2 0.44 34 30 70 11 0.88 2 0.28 208 29 65.9 8.9 1.1 0.17 1.9 0.26

While the invention has been described in detail with respect to thespecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and any equivalentsthereto.

1. A biodegradable, substantially continuous multicomponent filamentcomprising a first component and a second component, the first componentcontaining a first polyester having a melting point of from about 150°C. to about 250° C. and the second component containing a secondpolyester, wherein the second polyester is an aliphatic-aromaticcopolyester terminated with an alkyl group, hydroxyalkyl group, or acombination thereof, the aliphatic-aromatic copolyester having a meltflow index of from about 5 to about 200 grams per 10 minutes, determinedat a load of 2160 grams and temperature of 190° C. in accordance withASTM Test Method D1238-E.
 2. The biodegradable filament of claim 1,wherein the melt flow index of the copolyester is from about 15 to about50 grams per 10 minutes.
 3. The biodegradable filament of claim 1,wherein the copolyester has a number average molecular weight of fromabout 10,000 to about 70,000 grams per mole and a weight averagemolecular weight of from about 20,000 to about 125,000 grams per mole.4. The biodegradable filament of claim 1, wherein the copolyester has anumber average molecular weight of from about 20,000 to about 60,000grams per mole and a weight average molecular weight of from about30,000 to about 110,000 grams per mole.
 5. The biodegradable filament ofclaim 1, wherein the copolyester has a melting point of from about 50°C. to about 150° C.
 6. The biodegradable filament of claim 1, whereinthe copolyester has a glass transition temperature of about 0° C. orless.
 7. The biodegradable filament of claim 1, wherein the copolyesterhas the following general structure:

wherein, m is an integer from 2 to 10, in some embodiments from 2 to 4,and in one embodiment, 4; n is an integer from 0 to 18, in someembodiments from 2 to 4, and in one embodiment, 4; p is an integer from2 to 10, in some embodiments from 2 to 4, and in one embodiment, 4; x isan integer greater than 1; y is an integer greater than 1; and R₁ and R₂are independently selected from hydrogen; hydroxyl groups; straightchain or branched, substituted or unsubstituted C₁-C₁₀ alkyl groups; andstraight chain or branched, substituted or unsubstituted C₁-C₁₀hydroxalkyl groups.
 8. The biodegradable filament of claim 7, wherein mand n are each from 2 to
 4. 9. The biodegradable filament of claim 7,wherein the copolyester is derived from polybutylene adipateterephalate.
 10. The biodegradable filament of claim 1, wherein thefirst polyester is polylactic acid.
 11. The biodegradable filament ofclaim 1, wherein the filament has a sheath/core or side-by-sideconfiguration.
 12. A nonwoven web comprising the biodegradable filamentof claim
 1. 13. An absorbent article comprising an absorbent corepositioned between a substantially liquid-impermeable layer and aliquid-permeable layer, wherein the substantially liquid-impermeablelayer contains the nonwoven web of claim
 12. 14. The absorbent articleof claim 13, wherein the substantially liquid-impermeable layer forms anouter cover of the absorbent article.
 15. The absorbent article of claim14, wherein the nonwoven web is laminated to a breathable film. 16-37.(canceled)